Research suggests that stimulus awareness may inhibit affective responding to repeated, unreinforced stimulus exposures in Zajonc's (1968) "mere exposure effect" paradigm. The present studies are designed to test this hypothesis directly, and to investigate possible mechanisms underlying the inhibitory effects of stimulus awareness on the mere exposure effect. These experiments will test Bornstein's (1989b, 1990) attributional model of the mere exposure effect, which hypothesizes: 1) that subjects discount their affective reactions to clearly-recognized stimuli, attributing the experienced affect to the stimulus familiarization procedure; but 2) do not generate "discounting" attributions for subliminally-induced affect change. In the proposed experiments, subjects' ability to generate "discounting" attributions will be manipulated, and the effects of these manipulations on the magnitude of the exposure effect will be examined. By inducing discounting attributions, the magnitude of the subliminal mere exposure effect will be diminished. By preventing subjects from generating discounting attributions, the magnitude of the supraliminal exposure effect will be enhanced. Findings from these studies will not only increase basic knowledge regarding the role of conscious and unconscious mental processes in modulating affect, but also have implications for psychological treatment techniques that involve repeated stimulus exposures (e.g., systematic desensitization). Results of this research can be used to increase the efficacy of such treatment techniques, and may result in improved methodologies in laboratory paradigms that involve stimulus familiarization procedures.